Revert of Simple BlinkGC heap compaction.

third_party/WebKit/Source/platform/heap/Visitor.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/heap/Visitor.h"
 
 #include "platform/heap/BlinkGC.h"
 #include "platform/heap/MarkingVisitor.h"
 #include "platform/heap/ThreadState.h"
 #include "wtf/PtrUtil.h"
 #include <memory>
 
 namespace blink {
 
 std::unique_ptr<Visitor> Visitor::create(ThreadState* state,
                                          BlinkGC::GCType gcType) {
   switch (gcType) {
     case BlinkGC::GCWithSweep:
     case BlinkGC::GCWithoutSweep:
       return WTF::makeUnique<MarkingVisitor<Visitor::GlobalMarking>>(state);
-    case BlinkGC::GCWithSweepCompaction:
-      return WTF::makeUnique<
-          MarkingVisitor<Visitor::GlobalMarkingWithCompaction>>(state);
     case BlinkGC::TakeSnapshot:
       return WTF::makeUnique<MarkingVisitor<Visitor::SnapshotMarking>>(state);
     case BlinkGC::ThreadTerminationGC:
       return WTF::makeUnique<MarkingVisitor<Visitor::ThreadLocalMarking>>(
           state);
     case BlinkGC::ThreadLocalWeakProcessing:
       return WTF::makeUnique<MarkingVisitor<Visitor::WeakProcessing>>(state);
     default:
       ASSERT_NOT_REACHED();
   }
   return nullptr;
 }
 
 Visitor::Visitor(ThreadState* state, MarkingMode markingMode)
     : VisitorHelper(state), m_markingMode(markingMode) {
   // See ThreadState::runScheduledGC() why we need to already be in a
   // GCForbiddenScope before any safe point is entered.
-  DCHECK(state->isGCForbidden());
-#if ENABLE(ASSERT)
-  DCHECK(state->checkThread());
-#endif
+  state->enterGCForbiddenScope();
+
+  ASSERT(state->checkThread());
 }
 
-Visitor::~Visitor() {}
+Visitor::~Visitor() {
+  state()->leaveGCForbiddenScope();
+}
 
 }  // namespace blink